Johnson played for Cardiff at Wembley in 2008 when Cardiff lost to Portsmouth in the FA Cup final but it was his day this time around.
Johnson set up Zigic's goal to give Birmingham the lead before van Persie equalised and then Martins was gifted a winner for the Blues in the 89th minute.
Camerone Jerome came on to help run down the clock and Birmingham took major silverware.
Well done Birmingham. (Still upsets me though to think how close we came to winning the FA Cup).